Adjustable Magnetic Phase Transition Inducing Unusual Zero Thermal Expansion in Cubic RCo₂-Based Intermetallic Compounds (R = Rare Earth)

Abstract

Metallic materials that exhibit negligible thermal expansion or zero thermal expansion (ZTE) have great merit for practical applications, but these materials are rare and their thermal expansions are difficult to control. Here, we successfully tailored the thermal expansion behaviors from strongly but abruptly negative to zero over wide temperature ranges in a series of (Gd,R)­(Co,Fe)2 (R = Dy, Ho, Er) intermetallic compounds by tuning the composition to bring the first-order magnetic phase transition to second-order. Interestingly, an unusual isotropic ZTE property with a coefficient of thermal expansion of α l = 0.16(0) × 10–6 K–1 was achieved in cubic Gd0.25Dy0.75Co1.93Fe0.07 (GDCF) in the temperature range of 10–275 K. The short-wavelength neutron powder diffraction, synchrotron X-ray diffraction, and magnetic measurement studies evidence that this ZTE behavior was ascribed to the rare-earth-moment-dominated spontaneous volume magnetostriction, which can be controlled by an adjustable magnetic phase transition. The present work extends the scope of the ZTE family and provides an effective approach to exploring ZTE materials, such as by adjusting the magnetism or ferroelectricity-related phase transition in the family of functional materials.

Plastic and low-cost axial zero thermal expansion alloy by a natural dual-phase composite

“…But these artificial composites usually suffer from undesired microstructures or weak interfacial bonding, resulting in poor overall mechanical properties and thermal cycling performances. More importantly, the magneto-volume effect is highly composition-sensitive—a slight interfacial mass transfer during high-temperature synthesis may suppress or vanish the ZTE property 5 , 13 , 17 . The search for novel ZTE alloys with excellent strength-plasticity performance has been challenging for decades 18 – 22 .…”

Strong Coupling of Magnetism and Lattice Induces Near-Zero Thermal Expansion over Broad Temperature Windows in ErFe 10 V 2− x Mo x Compounds

“…To elaborately compensate MVEs and phonon-induced lattice expansion, the ZTE behaviors are usually limited in a narrow temperature window, even below liquid-nitrogen temperature. 9,10 Moreover, to achieve desirable coefficients of thermal expansions (CTEs) in these compounds, a common strategy is to modify the magnetic element (Fe, Co, or rare-earth) directly, which changes the magnetic interaction, as well as the total magnetic moments in the magnets and controls the thermal expansion behaviors.…”

Plastic and low-cost zero thermal expansion alloy by a natural dual-phase composite

“…To assess the comprehensive properties of the S-2, we summarized our results in Fig. 6a, ultimate strain versus compressive strength and ZTE temperature range (ΔT) for the ZTE alloy (S-2), compared with other typical ZTE or near ZTE metallic materials 5,7,8,11,12,15,18,[45][46][47][48][49] . One can see that ZTE intermetallic compounds are of low-strength and high-brittleness though they possess desirable zero thermal expansion performance.…”

“…However, ZTE performance is rare in nature. This behavior is especially unusual for metallic materials: only a few couplings among lattice, spin and orbital induces a reduced coe cient of thermal expansion by virtue of the so-called magneto-volume effect [4][5][6] , which so far has been reported in conventional Invar alloy 7 (Fe 0.64 Ni 0.36 ) and some magnetic intermetallic compounds (e.g., Tb(Co,Fe) 2 8 , La(Fe,Si,Co) 13 9 )…”

“…But these arti cial composites usually suffer from undesirable microstructures or weak interfacial bonding, resulting in poor mechanical properties and thermal stability. More importantly, the magneto-volume effect is highly composition-sensitive -a slight interfacial mass transfer during high-temperature synthesis may suppress or vanish the ZTE property 5,13,17 . The search for novel ZTE alloys with excellent strength-plasticity combination remains challenging for decades [18][19][20][21][22] .…”